engine harshness at high revs

imag

I agree that it's the valvetrain. That VVEL system is slick, but it somehow is causing more vibration than a well-refined camshaft, is my guess. I think it's worth it overall, but that's just me.

My counterpoint to the car mags is that Porsche flat sixes - every single one of them - sound like complete rubbish below 2000 RPM. They may sing a decent song above that, but the fact that 100K+ cars sound so much like VW Beetles at idle is inexcusable in my book.

tbonesteak

I took my maxima in for 60k mile service this weekend and spoke to a master tech at the dealer. He stated that the vhr motors' vertically rotating components of the vvel system is what was causing the harshness. Vertical as in components that rotate with the axis pointing in horizontal directions. He said that the vvel system has some imbalances to deal with at high rpms. He said it's the nature of this engine and stiffer mounts will help but only at high rpm operation. Don't know whether or not to believe him but he WAS the master tech. Hope this helps.

VTalumni

Is it getting better or could it be that you getting used to it?

__________________
'98 Ford zx2
'04 SRT-4
'07 Scion tc

need4speed

If I didn't want harsh n course and boominess n road n engine noise?
But be trying to buy an acura or lexus sedan.
Why the F&%K would I want a quiet race car!
And a slightly notchy stick is more fun 2.
F&#k the reviewers. Take the minor criticisms like those with less than a grain of salt.
The Z is perfect fun.

RCZ

Wow.

We aren't talking so much about sound here, its more the vibration at high RPM that bothers some of us I think. Just because its a sports car, it doesnt mean it should feel so coarse and out of control at high RPM. We go back to the same point over and over... and the fact of the matter is that an engine that is made to rev high and for sport driving should be MORE well balanced and exhibit LESS vibration. The engine internals are put through so much more stress, being a sports car and all, that it should be a LOT smoother to aid in its longevity.

Does that make sense to anyone else or is it just me being crazy?

Modshack

You're on the money....Coarsness bothers me. When an engine revs smoothly to redline it feels like everything is working in Harmony. Too bad it's not as good as the Hyundai Coupe in this regard. Certainly not as nice as my last Boxster. I tend to short shift at 6K as a result...

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iwantone09

i am heavily considering a 370. i've driven 3 370z's, first, a manual, then an automatic and then i went back and drove another manual. the reason i keep test drving them is because i needed to see if the rough engine and vibration in the shift knob was just in the first car i drove or was it a traight with all of them. when i first drove the car, i noticed a slight vibration in the shift knob of the manual. i honestly thought something was wrong because of the vibration i felt in my hand. that vibration disappeared with the auto. so i went back today at lunch and drove another manual and sure enough, i felt the vibration in my hand again. i could probably deal with it, but it would take some getting used to. as far as the engine, i didn't feel any vibration in the steering wheel or car, but all of them sounded rough when accelerating. it didn't purr like that g35's did when they came out. i currently have an 08 honda accord v6 coupe with a 3.5 motor. although my car has less power and torgue, my car is much smoother than the 370z. one of you guys talked about the size of the engine possibly beeing a culprit. based on what i've read, nissan probably should have kept the engine at 3.5 liters to keep the vibration down witout having to add so much counter balance. i don't know. i love the 370z and it's still on my list right now, but i will admit that coming from my silky smooth vtec v6 and drving my boys' bimmer 335, going to that rough engine would play heavy in my decision process. it's still a hell of a car though.

VTalumni

I am more concerned with the reliability of the automobile than the feeling when it is vibrating harshly. I mean is it going to shake things loose, destroy the engine prematurely, ruin the mounts, etc. Whether or not it is covered under warrenty, it would still bother me. You all think that is a concern?

__________________
'98 Ford zx2
'04 SRT-4
'07 Scion tc

RCZ

^ a little actually. I have a feeling the added stress will somewhat shorten the life of the engine. It just doesn't "feel" right. Oh well, I care, but not that much... Im pretty used to it already and if anything it helps me save a little gas.

tbonesteak

Yesterday i drove 3 different Zs in a continuing effort to pick one up as soon as possible. I'm noticing via these testdrives that dealers have 1 dedicated test car to let customers really experience the Z which is awesome. I have to admit that it's a case by case scenario. I paid EXTRA attention to certain aspects of the testdrive i.e., oil temps, vibration, tranny/drivetrain noise, etc. One of the cars vibrated significantly more than the other 5 i've driven in total. This one was vibrating so hard that it felt a bit painful to keep my hand firmly on the shifter at redline. I did this over and over with identical results. It does feel a bit weary regarding the long term outlook but if a ton of people's motors are dying at 80k, i think at that point we can set up something to approach Nissan. It was very interesting on this one tho. It wanted to explode!! hahah but in some weird way i like it!!!

Mr. C

I can feel some minor high rpm vibration from my G37 which is an auto. I'm guessing the heavy torque converter quells most of it. Definitely the biggest and only real weakness of these cars, the engine is 50 lbs overweight and poor NVH control. Nissan should have redone the VQ engine altogether from the ground up like Toyota did with their GR motor. Honda's J-series engine is super smooth and sounds nice but makes no power. Both Nissan and Honda need new V6 engines not anymore half-assed updates. With Honda you get no power and with Nissan you get tons of vibration, too much weight and a lack of power at lower revs. But with Toyota you get smoothness, peak power, a fat power band and lightweight construction.

Of course Nissan went ahead and built a completely new V6 engine exclusively for the GTR but apparently it is too much to ask from Nissan to give the people who actually pay their bills for an engine that doesn't thrash around. My friend's BMW M3 is completely smooth regardless of engine speed even up to its 8000 rpm redline.

And Porsche's new active engine mounts use magnetorheological fluid, I believe its a world's first.

VTalumni

But you also pay a lot more for the GT-R. Of course, you also get much more of a car from suspension to engine. I am definitely not using that as an excuse for Nissan because I believe that for 30k+ you should have a smooth running engine.

__________________
'98 Ford zx2
'04 SRT-4
'07 Scion tc

tbonesteak

How is the vq37vhr an half assed update? so VVEL which is a brand new technology that no other manufacturers use is an half assed update? I don't understand your logic. Find out how many parts on the 370 are different than that of the 350.

Mr. C

IMO, what's half-assed is Nissan's insistence to continually update the VQ rather than completely redesign the engine. The fact that Nissan added VVEL and has stated they'll add DI soon to their V6 engine range indicates Nissan is never going to redesign this motor, leaving buyers stuck with a coarse V6 engine well into the next decade.

This is a major design flaw. Pretty idiotic for Nissan to run around touting how they built a legitimate Cayman competitor, somehow I doubt Cayman owners ever have to deal with any engine roughness. All I'm saying is Nissan could and should have done better, for $30k+ buyers shouldn't have this problem.

VVEL isn't a brand new technology, BMW's Valvetronic has been around for some time. And Toyota's Valvematic system came out the same time as VVEL.

tbonesteak

other variations of the vq aren't coarse. this is the only one that's coarse. my vq35de in my maxima is smooth as butter but then again it doesn't produce the amount of powers the vhr does. from what i understand, camshaft-less technology that vvel features is not found in bmws and toyotas. correct me if i'm wrong. vq works. why change it? the design is so good that it's winning awards left and right every single year. no need to start on a new platform.